The present invention relates generally to distributed lighting systems, and, more particularly, to distributed lighting assemblies using low voltage light sources.
Recent advances in illumination technology have resulted in the prolific use of distributed lighting assemblies in many applications. For instance, considering a modern vehicle, distributed lighting is desirable in exterior applications such as lighted running boards for entry illumination to the vehicle. Distributed lighting systems are also used to decorate engine compartment illumination, trunk illumination, and interior accent lighting. See, for example, U.S. Pat. No. 6,244,734. In addition to vehicle applications, distributed lighting assemblies are desirable for decorative, accent, and safety lighting in business, homes, and outdoor illumination of sidewalks, swimming pools, steps, etc.
Conventional, distributed light assemblies include a high intensity light source and a plurality of light transmission conduits (e.g., fiber optic cables, light pipes, and the like) for illuminating locations remote from the light source. Aside from the expense of the light source and the light transmission members, routing light from the light source to a relatively large number of remote light outputs can become unmanageable. Further, bending the light transmission conduits during installation of distributed light assemblies is problematic to uniform light transmission through the cables.
To overcome at least some of these difficulties, a plurality of light sources (e.g., incandescent bulbs, halogen lamps, and the like) have been employed with an equal plurality of light transmission members to produce distributed lighting effects. It is difficult, however, to produce even lighting from the multiple light sources, and the assemblies are not as reliable as desired. Tubular light sources (e.g., neon, fluorescent, and the like) have been utilized to produce more even lighting, but are notably disadvantaged as requiring high voltage power supply converters to operate the tubes. Additionally, tubular light sources have poor impact resistance, rendering them unsuitable for many applications.
Recent technological advances in low voltage light sources, such as light emitting diodes (LEDs), now present low voltage light sources as viable candidates as light sources for distributed lighting assemblies. Low voltage light sources operate at a small fraction of the electrical power of conventionally used light sources and are an attractive option for use in distributed lighting assemblies due to generally lower cost and higher efficiency than conventionally used light sources. Thus far, however, obtaining a reliable and even light output from low voltage light sources in a distributed lighting assembly has proven difficult.
For example, with respect to LEDs, it has proven difficult to maintain the LEDs in a proper alignment with respect to light transmission conduits to produce even lighting from a distributed lighting assembly. Additionally, providing the LEDs in a sealed, impact resistant package suitable for rugged outdoor use and demanding environments, such as vehicle applications, is challenging. Further, during assembly and installation of the lighting assemblies, electrical connections to the LED contacts tend to be compromised and/or broken. Still further, the lower power LEDs entail current limiting features to energize the LED at an appropriate level for an extended life of the LED. Current limiting features can themselves present reliability issues in the distributed lighting assembly.